I guess it's not hard to be motivated during 'ups', the problem becomes wanting/needing to run myself to the ground, to the point of utter extreme exhaustion (usually accompanied with a complete loss of appetite, so you see how this can get messy). This usually makes me incredibly sore the next day, but luckily no injuries so far.
During downs...sometimes it's hard to get out , and sometimes I won't get out, but my ingrained self-discipline usually gets the better of me (thank goodness)--I put on my shoes almost as if automatically because running gives me such an incredible rush that it is like my body knows what it needs, and the endorphin high usually lasts an hour or two which is always nice. Running did wonders for me during my worst lows and is the one thing that I can safely say kept me above water.
I've been successfully able to stick to half-marathon trainings but when I'm not in training my running tends to be more instinctively based--I have great runs when I am very ****** off and/or restless and in a 'racing state' but if I'm actually 'stable' I usually feel less inclined to go run. With regards to what runs I do...well, in training I follow a strict schedule...long run/intervals/fartlek etc etc. For both highs and lows though the best are intense intervals or fartleks on treadmill or long run (12+ for me).
I just started medication and I'm a bit weary of that, but we'll see how my running does. I honestly feel it will suffer, cos my "instability" fuels me hehe. I'm kind of young (20) and have been running for 4 years, so relatively speaking I am new to acknowledging this diagnosis and realizing in retrospect how my running patterns have played-out these past few years.
moral of the story: running has been my saviour =]